Preparation of rhodium complex compounds

An organic one-phase process for preparing a halocarbonylbis(triorganophosphorus) rhodium compound which comprises reacting, at a temperature from about 20.degree. C. to about 200.degree. C., an essentially non-aqueous homogeneous organic reaction solution consisting essentially of (a) a rhodium complex concentrate, (b) a halide ion source, (c) carbon monoxide gas or a carbon monoxide source and (d) free triorganophosphorus ligand, for at least a sufficient period of time to form said halocarbonylbis(triorganophosphorus) rhodium compound;

• said rhodium complex concentrate consisting essentially of from about 0.1 to about 30 percent by weight of a spent hydroformylation reaction medium and having been produced by concentrating a spent hydroformylation reaction medium that contains a partially deactivated soluble rhodium complex hydroformylation catalyst, aldehyde products, higher boiling aldehyde condensation by-products, and free triorganophosphorus ligand, so as to remove from said medium, while retaining a major amount of the rhodium values of said catalyst present in said medium, at least essentially all of said aldehyde products, at least 50 percent by weight of said higher boiling aldehyde condensation by-products that have a boiling point below that of said free triorganophosphorus ligand present in said medium and at least 50 percent by weight of said free triorganophosphorus ligand present in said medium.